For uv maps, sure. Vertex paint is a no. It will not recognize different material colors on the mesh as actual color differences for printing purposes . Thus why you have to zip the UV texture file into the vrml file, so the Shapeways printer can find the the texture applied to the UV mapped model..
1. Add a material to the mesh
2. UV unwrap the mesh(Several techniques you can use to unwrap
3, Apply image to the material(Use UV mapping)
4. Zip the export with the image you used

Mesh lab(free) will show just about what Shapeways receives when you up load the model. But since if you opened up the image on your comp that has the file, no need to zip anything, until its uploaded to Shapeways

Have any questions regarding Blender, and need fast answers, you are always welcome at the IRC Server Freenode, channel #blender. As a bonus, several there have experience in modelling for 3D prints.

Vertex paint is a no. It will not recognize different material colors on the mesh as actual color differences for printing purposes.

I am not so sure about the vertex color ?
In the past I have succesfully uploaded vertex color models, and the site rendered them correctly, although I have not printed yet them.
But at the time Shapeways acknowledged this option.

I am currently testing some new vertex color models, but they they seem to choke the upload renderer. Probably size/complexity, will poll CS about it.

In the mean time, are there any good tools that convert from vertex color to UV maps? Seems like a difficult process..

I still can not figure out where I'm wrong ...
I did several tests, I am attaching the last: a simple cube with a mapping of bitmap color wood
I put everything in a compressed folder and load
but when I go to see the picture of the model of SW is no color

nothing to do ... I tried seven "cubes" with different settings: I saved both wrlm both X3d; cambbiato I kind of mapping, I have changed the type of image files.
in short, I tried everything but I can not see any kind of color in the file that SW charge!

I wrote some time ago to the support but they told me that they are not technicians and I have to read the guidelines. Well I know them by heart now!
possible that there is a "technical" SW to show me the way?

If your upload is successful then normally the SW image should show them. In the past there have been problems with the rotating image but the static one should be correct, i.e. no colours = has not worked.

I looked in your .wrl file and I can see no reference to the .rtex texture file. In your 3D software are you sure that you have correctly linked the Texture to the model? The problem is almost certainly in this area.

It seems that you have to change some setting in Rhino to make it actually apply the texture - as AmLachDesigns
wrote, the .wrl in your zip does not mention the texture file anywhere (it should have an ImageTexture entry with
the filename). Also, the "texture file" you included in the zip appears to be in some Rhino-specific format, while it
should be a regular jpg or png image. See if you can find any option in Rhino to "map" or "bake" the texture to the
model.
(And please create a new thread when you have new questions - or are you the "njcadman" from last july ?
Reviving a year-old discussion that is only tangentially related is confusing at best, and all previous contributors to the
thread will automatically receive an email notification while the topic may no longer be relevant to them)